<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>documentElement</title>
    <style type="text/css">
       /* body{
            border:20px solid #ccc;
            margin: 10px;
            padding:40px;
            background: #eee;
            width: 500px;
            height: 200px;
            overflow: scroll;
        }
        #mdiv{
            width: 400px;
            height: 200px;
            background: red;
            border: 1px solid #000;
            overflow: auto;
        }*/
    </style>
</head>
<body>
<script type="text/javascript">
    console.log(document);
    console.log(document.documentElement.clientHeight);
    console.log(document.body.clientHeight);
    //元素节点 nodeType=1 属性节点 nodeType=2 文本节点nodeType=3
    //注释元素 nodeType=8   文档元素 nodeType=9
</script>
</body>
</html>